gahnite
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Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at Broken Hill, Australia. Other occurrences include Falun, Sweden where it is found in pegmatites and skarns; and, in the United States, Charlemont, Massachusetts; Spruce Pine, North Carolina; White Picacho district, Arizona; Topsham, Maine; and Franklin, New Jersey.
Key facts
- Mineral.name
- Gahnite
- Mineral.category
- Oxide minerals Spinel group Spinel structural group
- Mineral.image
- Gahnite.jpg
- Mineral.imagesize
- 260px
- Mineral.formula
- ZnAl2O4
- Mineral.IMAsymbol
- Ghn
- Mineral.strunz
- 4.BB.05
- Mineral.system
- Cubic
- Mineral.class
- Hexoctahedral (mm) H-M symbol: (4/m 2/m)
- Mineral.symmetry
- Fdm
- Mineral.color
- Dark green, bluish green, blue to indigo, yellow to brown
- Mineral.habit
- Typically octahedra, rarely as dodecahedra also massive to granular
- Mineral.twinning
- Common on [111] produces striations
- Mineral.cleavage
- Indistinct parting on [111]
- Mineral.fracture
- Conchoidal, uneven
- Mineral.mohs
- 7.5–8.0
- Mineral.luster
- Vitreous
- Mineral.refractive
- n = 1.79–1.80
via Wikipedia infobox
Wikidata facts
- Image
- Gahnite-Spinel-3d33c.jpg
Show 6 more facts
- Strunz 8th edition (series ID, updated)
- IV/B.01a
- Nickel-Strunz 9th edition (updated 2009)
- 4.BB.05
- chemical formula
- ZnAl₂O₄
- Nickel-Strunz '10th ed', review of (9th ed/ 2009 update)
- 4.BB.05
- Commons category
- Gahnite
- IMA Mineral Symbol
- Ghn
Sources (1)
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- References
Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at Broken Hill, Australia. Other occurrences include Falun, Sweden where it is found in pegmatites and skarns; and, in the United States, Charlemont, Massachusetts; Spruce Pine, North Carolina; White Picacho district, Arizona; Topsham, Maine; and Franklin, New Jersey.
It was first described in 1807 for an occurrence in the Falu mine, Falun, Dalarna, Sweden, and named after the Swedish chemist, Johan Gottlieb Gahn (1745–1818), the discoverer of the element manganese. It is sometimes called zinc spinel.